지능형 U-Car에서 IEEE 802.11b을 이용한 차량 내 데이터 무선 랜 전송 성능 분석

이승환,허수정,박용완,이상신,이동학,유재황,Lee Seung-Hwan,Heo Soo-Jung,Park Yong-Wan,Lee Sang-Shin,Lee Dong-Hahk,Yu Jae-Hwang 대한전자공학회 2006 전자공학회논문지TC (Telecommunications) Vol.43 No.9

In this paper, we analyze the performance of IEEE 802.11b WLAN communication between access point(AP) and mobile equipment(ME) in 2.4 GHz band with noise and interference factors. WLAN communication at in-vehicle environment is assumed as the communication between main vehicle controller and electronic device such as sensor, ECU (Electrical Control Unit) in vehicle on telematics field for implementing wireless vehicle control system. Received interference level from other system's mobile equipment in the same band and automobile noise from each part of vehicle can be the main factors that can cause increasing error rate of control signal. With these (actors, we focus on the Eb/No the BER performance of WLAN for analyzing the characteristic of interference factors by the measured bit error rate.

갑상선 유두암에서 CK7, CK20, Vimentin, p53과 Ki-67의 발현

이승환,박승연,김나래<SUP>1<,SUP>,이영돈,Seung Hwan Lee,Seung Yeon Park,Na Rai Kim,<SUP>1<,SUP> and Young Don Lee 대한갑상선-내분비외과학회 2009 The Koreran journal of Endocrine Surgery Vol.9 No.1

알루미늄 하부층이 탄소나노튜브의 성장 및 전계방출 특성에 미치는 영향

이승환,곽정춘,이한성,이내성,Lee, Seung-Hwan,Goak, Jeung-Choon,Lee, Han-Sung,Lee, Nae-Sung 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.2

We studied the effect of an Al underlayer on the growth of carbon nanotubes (CNTs) and their field emission characteristics, First of all, CNTs were grown on the Invar catalyst layers with different thickness of 1 to 10 nm, showing that the CNT length was saturated for the catalyst 5 nm or thicker. The CNTs grown on the 5-nm-thick catalyst were ${\sim}10{\mu}m$ long and ${\sim}30nm$ in diameter. Second, an Al underlayer was applied between the catalyst layer and the Ti diffusion barrier to reduce the diameters of CNTs for better field emission properties by forming spherical Al oxide particles on which smaller catalyst nanoparticles would occur. The optimal thickness of an Al underlayer underneath the 5-nm-thick catalyst was ${\sim}15nm$, producing the CNTs with the length of ${\sim}15{\mu}m$ and the diameter of ${\sim}15nm$. The field emission measurements, following the tape activation, showed that the thinner and longer CNTs gave rise to better field emission performance with the lower turn-on and threshold electric fields.

한우 지방산결합단백질 4(FABP4) 유전자 조절영역내 단일염기변이(SNP)와 도체형질간 연관성 분석

이승환,김남국,김승창,최봉환,허강녕,이창수,김언현,이준헌,김형철,홍성구,Lee, Seung-Hwan,Kim, Nam-Kuk,Kim, Seung-Chang,Choi, Bong-Hwan,Heo, Kang-Neung,Lee, Chang-Soo,Kim, Oun-Hyun,Lee, Jun-Heon,Kim, Hyeong-Cheul,Hong, Seong-Koo 충남대학교 농업과학연구소 2011 Korean Journal of Agricultural Science Vol.38 No.4

The aim of this study was to identify the polymorphism on fatty acid binding protein (FABP4) gene promoter region and its association with carcass traits in Hanwoo. We performed PCR-direct sequencing of FABP4 promoter region to identify single nucleotide polymorphism (SNPs) using unrelated 24 Hanwoo bulls. Four SNPs (-298A>G, -472A>G, -887A>G, -862A>G) were detected in the promoter region and genotyped on 583 Hanwoo steers. A linear mixed model revealed an association of three SNPs (-298A>G, -472A>G and -862A>G) with carcass weight and marbling score in dominance model (P<0.05). The animals with AA genotypes for the three SNPs were heavier carcass weight (5 kg) than animals with GG genotypes in the statistical analysis. For the marbling score, the AA genotype was lower effect of marbling score (0.21) than GG genotypes. In conclusion, this study indicates an important role for three SNPs detected in promoter region of FABP4 in determining carcass weight and marbling score in Hanwoo.

ZnO와 CuO 첨가에 따른 NKN-LST 세라믹스의 압전 특성

이승환,이성갑,이영희,Lee, Seung-Hwan,Lee, Sung-Gap,Lee, Young-Hie 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.8

Additions (ZnO, CuO) doped $0.98(Na_{0.5}K_{0.5})NbO_3-0.02Li(Sb_{0.17}Ta_{0.83})O_3$ (0.98NKN-0.02LST-x) lead free piezoelectric ceramics have been fabricated by ordinary sintering technique. The effects of additions doping on the dielectric, piezoelectric, and ferroelectric properties of the ceramics were mainly investigated. X-ray diffraction of the sample appeared orthorhombic phase. The specimen doped with additions exhibits enhanced electrical properties ($d_{33}$= 153 pC/N). These results indicate that the 0.98NKN-0.02LST-x ceramics is a promising candidate for lead-free piezoelectric ceramics for applications such as piezoelectric actuators, harmonic oscillator and so on.

CuO와 ZnO 첨가에 따른 NKN-BZT 세라믹스의 압전 특성

이승환,백상돈,이동현,이성갑,이영희,Lee, Seung-Hwan,Baek, Sang-Don,Lee, Dong-Hyun,Lee, Sung-Gap,Lee, Young-Hie 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.8

The lead-free $0.98(Na_{0.5},K_{0.5})NbO_3-0.02Ba(Zr_{0.52},Ti_{0.48})O_3$-(hereafter NKN-BZT) CuO, ZnO-doped ceramics were prepared using a conventional mixed oxide method. NKN-BZT ceramics doped CuO, ZnO have superior structural and electrical properties than pure NKN-BZT ceramics. For the NKN-BZT-ZnO ceramics sintered at $1,120^{\circ}C$, piezoelectric constant ($d_{33}$) of sample showed the optimum values of 172 pC/N. The $0.98(Na_{0.5},K_{0.5})NbO_3-0.02Ba(Zr_{0.52},Ti_{0.48})O_3$-ZnO ceramics are a promising candidate for lead-free piezoelectric materials.

NKN-(1-x)BNT-xBT 세라믹스의 압전 및 유전특성

이승환,남성필,이성갑,이영희,Lee, Seung-Hwan,Nam, Sung-Pill,Lee, Sung-Gap,Lee, Young-Hie 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.10

In this study, piezoelectric and dielectric properties of the $(Na_{0.5}K_{0.5})NbO_3-(1-x)(Bi_{0.5}Na_{0.5})TiO_3-xBaTiO_3$ [NKN-(1-x)BNT-xBT] ceramics were investigated. The lead-free NKN-(1-x)BNT-xBT ceramics were fabricated by a conventional mixed oxide method. The results indicate that the addition of $BaTiO_3$ significantly influences the sintering, microstructure, phase transition and electrical properties of NKN-BNT ceramics. A gradual change in the piezoelectric and dielectric properties was observed with the increase of BT contents. The dielectric constant, piezoelectric constant ($d_{33}$) and electromechanical coupling factor ($k_p$) increased at the morphotropic phase boundary (MPB). The $d_{33}$=184 pC/N, $k_p$=0.38, dielectric constant=1455 with dielectric loss value of less than 1% were obtained for the NKN-0.95BNT-0.05BT ceramics sintered at $1150^{\circ}C$ for 2h. These results demonstrate that the NKN-(1-x)BNT-xBT ceramics is an attractive candidate for lead-free piezoelectric materials.

4-10 Hz 빛과 소리자극 후 단기기억력 및 자율신경심장기능의 변화 - 예비연구 -

이승환,김진환,박중규,이경욱,양대현,홍근영,채정호,Lee, Seung-Hwan,Kim, Jin-Hwan,Park, Joong-Kyu,Lee, Kyung-Uk,Yang, Dae-Hyun,Hong, Keun-Young,Chae, Jeong-Ho 대한수면의학회 2004 수면·정신생리 Vol.11 No.1

Objectives: Sound and light (SL) stimulation has been used as a method to induce some useful mental states in the fields of psychology and psychiatry. It is believed that sound and light entrainment device (SLED) has some specific effects through synchronization of EEG in patients who use it. Theta frequency is believed to stimulate deep relaxation and short term memory processing. This study was conducted to evaluate if 4-10 Hz SL stimulation can induce relaxation and improve short term memory function. Methods: Ten medical students with no medical or psychiatric problems participated in this study. Subjects were randomly divided into two groups. One group was applied with real SLED was applied to one group (R group) and pseudo SLED to the other group (P group). The two groups were exposed to SL stimulation with SLED 15 minutes a day for 5 days, and after two days rest the two groups were switched over. The Korean Wechsler Adult Intelligence Scale (K-WAIS), Academic Motivation Tests (AMT), Test Anxiety Scale (TAS), Korean Auditory Verbal Learning Test (K-AVLT), and digit span were used to evaluate short term memory. Spielberger's State-Trait anxiety inventory and heart rate variability (HRV) test were used to evaluate degree of relaxation. Results: Compared with S group, R group showed a significant improvement in K-AVLT and digit span after a single application of SL stimulation. But 5-day long application did not reveal any differences between the two groups. A significant change in HRV was observed in 5-day long application of SL stimulation after being switched over to other SLED. Conclusion: This pilot study suggests that 4-10 Hz SL stimulation has some positive influences on short term memory and relaxation.

PET/CT 검사에서 Stomach의 추가 촬영을 줄이기 위한 수분 섭취의 유용성

이승환,배성복,정병곤,이규찬,이광철,배원규,Lee, Seung-Hwan,Bae, Seong-Bok,Jeong, Byeong-Gon,Lee, Gyu-Chan,Lee, Gwang-Cheol,Bae, Won-Gyu 대한핵의학기술학회 2011 핵의학 기술 Vol.15 No.1

Purpose: With the introduction of PET since 1994, test methods have made rapid progress. Accordingly, the studies on the diagnosis and treatment of cancer as well as treatment response evaluation PET test are useful. However, it is difficult to divide stomach lesions and secretion. The purpose of this study is to reduce additional shooting by dividing lesions and secretion of stomach. Materials and Method: This study aiming at total 228 cancer patients was conducted from Aug 18 to Sep. 10, 2010. Among them, 115 patients had a test without water intake before shooting from Aug. 8 to 31 and 113 had a test after drinking 500 cc water right before shooting from Sep. 1 to 10 The Discovery ST PET/CT (GE Healthcare, USA) was used, and pearson's chi-square test was conducted to analyze significance through SPSS (Ver.18). Results: Among the total 228 cancer patients, there were 115 who had a test without water intake before shooting, 89 who had no double additional shooting, 13 who had stomach additional shooting and 13 who had other additional shooting. In addition, 109 had no additional shooting among 113 who had a test after taking 500 cc water, 1 had stomach additional shooting and 3 had other additional shooting. According to the findings above, the patients who had a test without water intake show reduced additional shooting, but for more exact significance, pearson's Chi-square test was carried out and the significance percentage was 0.001 that is smaller than 0.05, which means two groups have a significant relationship. As the minimum expectation frequency was 6.94 and there was no expectation frequency smaller than 5, so that it doesn't need to carry out pearson's exact verification. Conclusion: The above analysis has found that if one drinks 500cc water before the test, not only stomach additional shooting but also other additional shooting can be dramatically reduced, and test delay can be also reduced.

비납계 0.98 (Na_0.44K_0.52)Nb_0.84O₃-0.02Li_0.04 (Sb_0.06Ta_0.1)O₃-0.5 mol%CuO 세라믹스의 전기적, 구조적 특성

이승환,남성필,이성갑,이영희,Lee, Seung-Hwan,Nam, Sung-Pill,Lee, Sung-Gap,Lee, Young-Hie 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.2

The 0.98 ($Na_{0.44}K_{0.52})Nb_{0.84}O_3-0.02Li_{0.04}$ ($Sb_{0.06}Ta_{0.1})O_3-0.5$ mol%CuO ceramics have been fabircated by ordinary sintering technique and the effect of various calcination method on the electrical propertis and microstructure have been studied. It was observed that the various calcination method influenced the elelctrical properties and structural properties of the 0.98NKN-0.02LST-0.5 mol%CuO ceramics with the optimum piezoelectric constant ($d_{33}$) and electromechanical coupling factor ($k_p$) at room temperature of about $155{\rho}C/N$ and 0.349, respectively, from 0.98NKN-0.02LST-0.5 mol%CuO ceramics sample. The curie temperature ($T_c$) of this ceramic was found at $440^{\circ}C$. The 0.98NKN-0.02LST-0.5 mol%CuO ceramics are a promising lead-free piezoelectric ceramics.